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This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2023 Paulo Moura <pmoura@logtalk.org> SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

% start by loading the example:

| ?- logtalk_load(reflection(loader)). ...

% print the (public and protected) interface of each class:

| ?- object::print, abstract_class::print, class::print.

Object: object

interface: new/1 delete/1 instances/1 metaclass/0 abstract_class/0 strict_instance/0 print/0

Object: abstract_class

interface: new/1 delete/1 instances/1 metaclass/0 abstract_class/0 strict_instance/0 print/0

Object: class

interface: new/1 delete/1 instances/1 metaclass/0 abstract_class/0 strict_instance/0 print/0

yes

% class is the metaclass of all classes:

| ?- class::instances(Instances), class::metaclass.

Instances = [class,abstract_class,object] yes

% create an abstract_class, check it and print its interface:

| ?- abstract_class::new(ac), ac::abstract_class, ac::print.

Object: ac

interface: metaclass/0 abstract_class/0 strict_instance/0 print/0

yes

% try to create an instance of the abstract class:

| ?- ac::new(i).

uncaught exception: error(existence_error(predicate_declaration,new(i)),ac::new(i),user)

% create a new instantiable class and print its interface:

| ?- class::new(c), c::print.

Object: c

interface: new/1 delete/1 instances/1 metaclass/0 abstract_class/0 strict_instance/0 print/0

yes

% create an instance of the new class:

| ?- c::new(i), c::instances(Instances).

Instances = [i] yes

% because c does not declare any predicates, its instances have no interface:

| ?- i::current_predicate(Predicate).

no

% create an instance of object, root of the inheritance graph, and print its interface:

| ?- object::new(j), j::print.

Object: j

interface: strict_instance/0 print/0

yes

% delete the dynamic objects that we created:

| ?- c::delete(i), class::delete(c), abstract_class::delete(ac), object::delete(j).

yes